It's not strictly forbidden to submit a link to a site that you own or otherwise benefit from in some way, but you should sort of consider yourself on thin ice. So please pay careful attention to the rest of these bullet points.

If you spend more time submitting to reddit than reading it, you're almost certainly a spammer.

If your contribution to Reddit consists mostly of submitting links to a site(s) that you own or otherwise benefit from in some way, and additionally if you do not participate in discussion, or reply to people's questions, regardless of how many upvotes your submissions get, you are a spammer.

If people historically downvote your links or ones similar to yours, and you feel the need to keep submitting them anyway, they're probably spam.

If people historically upvote your links or ones like them -- and we're talking about real people here, not sockpuppets or people you asked to go vote for you -- congratulations! It's almost certainly not spam. But we're serious about the "not people you asked to go vote for your part.

If nobody's submitted a link like yours before, give it a shot. But don't flood the new queue; submit one or two times and see what happens.

For right now, this is just a friendly message, but here in /r/Minecraft, we take action against anyone that fits the above definition.